/Engine/Plugins/2D/Paper2D/Source/Paper2DEditor/Public/PaperJSONHelpers.h
Returns true if the field named Key is a Number, populating Out_Value, or false if it is missing or the wrong type (Out_Value is set to 0.0f on failure)
static bool ReadFloatNoDefault ( const [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< class [FJsonObject](API\Runtime\Json\Dom\FJsonObject) > Item, const [FString](API\Runtime\Core\Containers\FString) & Key, float & Out_Value )